When the amplitude of an input signal is small, the frequency converter is susceptible to the influence of noise and has a problem that it is not possible to correctly convert the frequency of the input signal.
Conventionally known frequency converters additionally input a current in a voltage-current converter to provide the difference between the amount of a direct current which flows into a switching step and the amount of a current which flows into the voltage-current converter. Consequently, it is possible to reduce noise that is produced in the switching step and to operate the switching step even with a local signal having small amplitude.
However, the conventional frequency converters additionally supply the current to the voltage-current converter, and therefore increase power consumption.
Therefore the present invention provides a frequency converting circuit, a signal processing circuit and a receiver which can convert the frequency even if the amplitude of a local signal is small and which can suppress an increase of power consumption.